1. Field of Invention
The present invention relates to an anchor rod for an attachment anchor and which is secured with a hardenable organic and/or inorganic mortar mass in a receiving bore, includes an anchoring region and is provided with load application means.
2. Description of the Prior Art
Two anchoring methods proved themselves capable of providing a substantially expansion pressure-free attachment. One of the methods consists in that an anchor with expandable segments is secured in an undercut in the base of a receiving bore. The segments are swung out in the region of the undercut and retain the anchor axially by form-lockingly engaging the undercut. This attachment method is relatively expensive. First, a receiving bore needs to be formed, and then an undercut should be formed at a pre-determined depth of the receiving bore with a special tool. Only then, the anchor can be set into the receiving bore. The swinging of the retaining segments is effected, for example, by axially pulling in or pressing out a cone. How much the attachment is expansion pressure-free is determined by an angle at which the bore wall extends in the transitional region between the bore and the undercut.
A simpler method of forming of expansion pressure-free attachments consists in securing of an anchor rod in a receiving bore with a hardenable organic or inorganic mortar mass. To this end, the receiving bore, after it is formed, is filled with a mortar mass. As a rule, the used mortar masses represent multi-component systems with reactive components and additives which should be stored separately from one another. The hardening reaction takes place only during the contact and mixing of the components with each other inside the receiving bore. The mortar mass components, which react with each other, are stored, e.g., in glass ampullas or in foil bags separately from each other, and are placed in a bore in these containers. With subsequent insertion of the anchor rod, the glass ampullas and the foil bags are broken, and the components contact each other. To insure firmness of the bonding mortar and to achieve a highest possible retaining value, it is important that the components of the mortar mass are well mixed with each other. Therefore, generally, the anchor rod is inserted in the receiving bore while being rotated about its axis. The profile of the anchoring region of the anchor rod should improve the intermixing of the components. In addition to intermixing of the components of the mortar mass, the anchor rod has another function, namely, to comminute the glass ampullas and/or the foil bags. This should be done to an extent which insures that the retaining value is not adversely influenced by large residual pieces of glass or foil adhered to the receiving bore wall.
While the known geometry of the anchor rod, as a rule, insures an adequate intermixing of the components and essentially satisfactory comminution of the component containing sheathes, a need in a further improvement exists. The comminution process should be affected more rapidly. The sheathes, in particular the foil bags, need to be comminuted to a greater extent. Deposition of the parts of the components of the mortar mass on the bottom of the receiving bore should be prevented to a greatest possible extent. The mortar mass should be mixed as homogeneously as possible and be distributed along the axial length of the anchoring region of the anchor rod. In equal measure, the flow of the mortar mass out of the receiving bore during the mixing process should be prevented. The trailing section of the anchor rod, which is provided with load application means, e.g., an outer thread, should remain free from the mortar mass. A further, not unimportant object of the invention is to provide an anchor rod for an attachment anchor which would have good secondary expansion characteristics in a fissure-prone bore. The anchor rod should have a geometry and a structure that would ensure a crack-proof capability of the attachment anchor. At that, the anchor rod should be capable of being secured in one step and should not require any additional auxiliary means besides a percussion drill tool for its setting.